1. Field of the Invention
This invention relates generally to methods for prophylaxis against diseases transmittable by sexual contact and more particularly to methods for prophylaxis of HIV transmission. The invention also relates to combinations of compositions and devices used with such methods.
2. Background Information
The need to develop simple, effective and low cost methods to prevent HIV transmission between individuals is an important strategy to manage HIV infection. Recent developments that have identified new more virulent strains of HIV, coupled with the suggestion that certain current therapies may be less effective than they were in the past, have heightened the need to develop methods to circumvent primary HIV infection from sexual contact.
In addition to HIV, many diverse diseases are transmitted sexually. Among the more common are condylomata acuminata (veneral warts), gonorrhea, syphilis, herpes simplex, granuloma cenereum, chancroid, granuloma inguinale, non-gonococcal urethritis, acute pelvic inflammatory disease, vaginitis and anorectal disease.
Although several methods for prophylaxis of these diseases are known, no universally satisfactory method has been developed. In theory, the best way to prevent transmission is abstinence, but in reality this is often impractical and not followed. Other methods involve the insertion of physical barriers to prevent the direct contact of bodily fluid between individuals. However, such methods are often inconvenient, requiring user acquiescence. Moreover, the barriers themselves sometimes fail, negating any potential prophylactic benefits.
More targeted prophylactic methods involve destroying HIV itself so that it is incapable of invading the recipient tissue. Such methods involve the administration of biologically active materials to the vagina, for example. Nonoxynol-9® is known to have bacteriocidal action and to be capable of destroying HIV. However, the use of Nonoxynol-9® and other spermicidal and bacteriocidal agents in vaginally inserted suppositories, creams, foams or the like, are discouraged because of the risk of causing mucosal inflammation. In addition, these agents tend to destroy the healthy bacterial flora of the vagina and often lead to yeast infections. Specifically, the use of Nonoxynol-9® has been reported to result in an increased risk of HIV infection among prostitutes. Kreiss et al., JAMA 268(4):477-482 (1992), which is incorporated by reference herein.
Other methods to destroy HIV in seminal fluid involve the use of antiseptics containing iodine, for example. (U.S. Pat. No. 5,545,401). However, such methods often require vigilance by the user to ensure that irritation does not result. Another method employs the use of zinc salt containing genital lubricants, in which the user spreads the lubricant on a genital surface to create an anti-viral chemical barrier. (U.S. Pat. No. 5,624,675). However, some individuals may choose not to use such a method due to the uncertain effects that zinc may have upon entry into the bloodstream.
It has been observed that HIV is relatively rarely transmitted by oral secretions. In fact, the saliva of viremic individuals usually contains only noninfectous components of HIV indicating virus breakdown. This has been reported to be due to hypotonic disruption by which saliva kills infected mononuclear leukocytes and prevents their attachment to mucosal epithelial cells and production of infectious HIV. (Baron et al., Arch. Intern. Med. 159:303-310 (1999)). Although saliva could be used as a method for prevention of HIV transmission in oral, vaginal and rectal intercourse, the hypotonic preventative effect of saliva would be negated by the relatively larger quantity of isotonic semen.
Thus, there exists a need for less irritating substances which prevent the transmission of sexually transmitted diseases, as well as the transmission of HIV-infected leukocytes in seminal fluid or HIV in free form. In addition, there is a need for a method in which the preventative properties of the substances remain intact relative to the volume of semen typically introduced. Finally, there is a need for methods for prophylaxis which are simple and convenient to use both vaginally and rectally. The present invention satisfies these needs and provides related advantages as well.